If never let them see you cry is the female executive’s bulletproof vest, police Chief Cathy Lanier went in bare at her teary swearing-in ceremony at the Tivoli Theatre this afternoon.

And who could blame her, what with the dim lights, the woman fingering a syrupy version of “Waiting on the World to Change” on the electric keyboard, and remember-back-when speeches by Mayor Adrian Fenty and her friend, New York City fire chief Joe Pfieffer.

When Lanier spoke, it was about growing up on food stamps, sneaking in puppies, dropping out of school at 15, being a teenaged single mother, getting her G.E.D., and turning it around with the help of her mother, who was in the crowd, sporting a keychain hanging from her purse that read “I Have P.M.S. and a Gun” (though hopefully not in the District of Columbia just yet).

Along the way, a female officer near the front row passed a bunch of tissues up to the chief.

When it was over, and the room got quiet, someone in the crowd couldn’t hold back.

“Miss Chief! You can cry when you want to,” she yelled.